I. Field of the Invention
The present invention relates generally to determining a desired trajectory and/or monitoring the trajectory of surgical instruments and implants and, more particularly, doing so during spinal surgery, including but not limited to ensuring proper placement of pedicle screws during pedicle fixation procedures and ensuring proper trajectory during the establishment of an operative corridor to a spinal target site.
II. Discussion of the Art
Determining the optimal or desired trajectory for surgical instruments and/or implants and monitoring the trajectory of surgical instruments and/or implants during surgery have presented challenges to surgeons since the inception of surgery itself. One example is pedicle fixation, which is frequently performed during spinal fusions and other procedures designed to stabilize or support one or more spine segments. Pedicle fixation entails securing bone anchors (e.g. pedicle screws) through the pedicles and into the vertebral bodies of the vertebrae to be fixed or stabilized. Rods or other connectors are used to link adjacent pedicle screws and thus fix or stabilize the vertebrae relative to each other. A major challenge facing the surgeon during pedicle fixation is implanting the pedicle screws without breaching, cracking, or otherwise compromising the pedicle wall, which may easily occur if the screw is not properly aligned with the pedicle axis. If the pedicle (or more specifically, the cortex of the medial wall, lateral wall, superior wall and/or inferior wall) is breached, cracked, or otherwise compromised, the patient may experience pain and/or neurologic deficit due to unwanted contact between the pedicle screw and delicate neural structures, such as the spinal cord or exiting nerve roots, which lie in close proximity to the pedicle. A misplaced pedicle screw often necessitates revision surgery, which is disadvantageously painful for the patient and costly, both in terms of recovery time and hospitalization.
The present invention is aimed primarily at eliminating or at least reducing the challenge associated with determining the optimal or desired trajectory for surgical instruments and/or implants and monitoring the trajectory of surgical instruments and/or implants during surgery.